The EU must do more to address the danger posed by chemical cocktails in lakes, rivers and streams, even if individual substances are present at lower concentrations, writes the European Environment Agency (EEA) in a new report.

While significant progress across the EU has been made in dealing with hazardous chemicals, low concentrations of substances could have negative effects when combined with other chemicals (the so-called cocktail effect).

The EEA report cautions that there are many more chemicals present in the environment, where better information and knowledge is needed to know whether they present a risk in lakes, rivers and other surface waters.

A key concern involves micro pollutants and mixtures of single chemical substances that individually may be present at harmless concentrations can combine and pose a risk to health. In the environment, chemicals entering surface waters can mix with natural mineral salts and organic compounds, as well as with nutrients from sewage, agricultural run-off and other waste water. Chemicals which make their way into the water from air emissions add to the mix. The report notes that the detection of several hundred organic chemicals at low concentrations in a single freshwater sample is common and the level of risk that that might present is insufficiently understood.

The EEA warns that recent scientific developments in the evaluation of chemical blends are not sufficiently reflected in the EU rules. It calls for more robust data reporting on chemical emissions and better monitoring, modelling and reporting of diffuse sources of pollution to ensure that action can be taken appropriately.

Last reviewed 31 January 2019